There are communication networks that are discussed in the related art in which messages are transmitted in accordance with serial communication protocols (e.g. Controller Area Network (CAN), FlexRay, Local Interconnect Network (LIN), Media Oriented Systems Transport (MOST)). The networks include at least one data bus, to which multiple user nodes are connected. In these communication networks, it is further understood not to use all of the messages sent over the data bus from all of the user nodes connected to the data bus. The user nodes each include one communication module and one application. To relieve the host application in the user nodes, many communication modules only forward those messages to the application that will indeed be used in the application. For this purpose, the messages are detected on the basis of their numeric identifier. This method is called acceptance filtering. The known methods for acceptance filtering include lists of identifiers that are to be allowed through (so-called acceptance codes). Parts of the identifiers may be masked out for the purpose of filtering such that each list entry may stand for a group of identifiers (so-called acceptance mask). To this end, respectively n bits of the identifier may be masked out by a mask such that the identifier stands for a group of 2n identifiers. The known method may be varied by lists of identifiers, which are not to be accepted, that is, which are to be blocked. These lists are configurable by software.
If an application uses messages from a broad spectrum of identifiers, it may happen that the filter options of the hardware communication module are insufficient to allow all required messages to pass through and at the same time to block all superfluous messages. For the remaining acceptance filtering, the application software must then expend processing power of the processing unit (e.g. central processing unit; CPU) of the user node. In addition, other sizes of the groups defined by the acceptance masks are possible only by overlap in that multiple list entries are considered simultaneously and combined. This requires time and hardware resources, however. Another disadvantage of filtering using acceptance codes and acceptance masks is the danger that desired messages are inadvertently rejected. To prevent this, the acceptance mask is usually opened very wide, which has the consequence that messages are accepted that are actually not used by the application. As a result, the application software bears additional load (frequent operation of the FIFO for retrieving the message, filtering the message etc.).